(a) Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display for widening a viewing angle.
(b) Description of the Related Art
Generally, a liquid crystal display has two panels with electrodes, and a liquid crystal layer interposed between the two panels. Voltages are applied to the electrodes so that the liquid crystal molecules in the liquid crystal layer are re-oriented to thereby control light transmission.
Liquid crystal displays are widely used because they exhibit excellent display characteristics, but they do have a major shortcoming when their viewing angle is narrow. Various techniques for widening the viewing angle have been developed. For instance, liquid crystal molecules may be aligned perpendicular to top and the bottom panels while forming a predetermined pattern of openings or protrusions at a pixel electrode and a common electrode.
In the case of formation of the opening pattern, the liquid crystal molecules are controlled in orientation by way of a fringe field due to the opening pattern formed at the pixel electrodes and/or the common electrode.
In the case of formation of the protrusion pattern, protrusions are formed at the pixel electrode and/or the common electrode, and the liquid crystal molecules are controlled in orientation by way of electric field deformed due to the protrusion pattern.
Furthermore, it is proposed that an opening pattern is formed at the pixel electrode while forming a protrusion pattern at the common electrode. The liquid crystal molecules are controlled in orientation by way of the fringe field due to the opening pattern and the protrusion pattern while forming a plurality of domains.
In such a multi-domain liquid crystal display, the viewing angle per contrast ratio of 1:10 or the viewing angle defined as the limit angle of the inter-gray scale brightness inversion reaches 80° or more in all directions. However, if the lateral gamma curve is deviated from the front gamma curve, visibility at left and right sides is deteriorated, even when compared to the twisted nematic (TN) mode liquid crystal display. For instance, in a patterned vertically aligned (PVA) mode where opening portions are formed for the domain partitioning, the display becomes much brighter as it comes to the lateral side, and the color becomes white. In a serious case, the bright gray scales are removed while conglomerating the picture images. Thus, it is desirable to reduce deterioration of colors on the left and right sides, thereby enhancing the image quality of an LCD.